Pool strings in JsonReader.
Pool strings in JsonReader.

This yields a 10% improvement in parsing both Twitter and Google Reader
streams.

Change-Id: Ifc238777e929b5b3e9a4480098b315e418378f8b
http://b/3201883

xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base